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PDF MAX6660 Data sheet ( Hoja de datos )
| Número de pieza | MAX6660 | |
| Descripción | Remote Junction Temperature Controlled Fan Speed Regulator | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-2225; Rev 0; 10/01
Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
General Description
Features
The MAX6660 is a remote temperature sensor and fan-
speed regulator that provides a complete fan-control
solution. The remote temperature sensor is typically a
common-collector PNP, such as a substrate PNP of a
o Integrated Thermal Sensing and Fan-Regulation
Solution
o Programmable Fan Threshold Temperature
microprocessor, or a diode-connected transistor, typi- o Programmable Temperature Range for Full-Scale
cally a low-cost, easily mounted 2N3904 NPN type or
2N3906 PNP type.
The device also incorporates a closed-loop fan con-
mtroller that regulates fan speed with tachometer feed-
back. The MAX6660 compares temperature data to a
ofan threshold temperature and gain setting, both pro-
grammed over the SMBus™ by the user. The result is
.cautomatic fan control that is proportional to the remote-
junction temperature. The temperature feedback loop
can be broken at any time for system control over the
Uspeed of the fan.
t4Fan speed is voltage controlled as opposed to PWM
controlled, greatly reducing acoustic noise and maxi-
mizing fan reliability. An on-chip power device drives
efans rated up to 250mA.
Temperature data is updated every 0.25s and is read-
eable at any time over the SMBus interface. The
hMAX6660 is accurate to 1°C (max) when the remote
junction is between +60°C to +100°C. Data is formatted
as a 10-bit + sign word with 0.125°C resolution.
SThe MAX6660 is specified for -40°C to +125°C and is
taavailable in a 16-pin QSOP package.
Applications
aPC
Notebooks
.DTelecom Systems
Industrial Control Systems
wServers
wwWorkstations
Fan Speed
o Accurate Closed-Loop Fan-Speed Regulation
o On-Chip Power Device Drives Fans Rated
Up to 250mA
o Programmable Under/Overtemperature Alarms
o SMBus 2-Wire Serial Interface with Timeout
(Cannot “Lock Up” the SMBus)
o Supports SMBus Alert Response
o ACPI Compatible, Including OVERT System
Shutdown Function
o ±1°C (+60°C to +100°C) Thermal-Sensing Accuracy
o MAX6660EVKIT Available
Ordering Information
PART
MAX6660AEE
TEMP. RANGE
-40°C to +125°C
PIN-PACKAGE
16 QSOP
Typical Operating Circuit
0.1µF
+12V
+3V TO +5.5V
50Ω
10kΩ
EACH
5kΩ VFAN VCC STBY
1µF FAN
TACH IN
SMBCLK
FAN MAX6660
SMBDATA
CLOCK
DATA
SMBus is a trademark of Intel Corp.
DXP
2200pF
ALERT
INTERUPT
TO µP
Pin Configuration appears at end of data sheet.
PENTIUM
DXN
AGND
OVERT
ADD0 ADD1 PGND
TO SYSTEM
SHUTDOWN
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
Pin Description
PIN NAME
FUNCTION
1
VFAN
Fan Drive Power-Supply Input. 4.5V to 13.5V.
2 VCC Supply Voltage Input. +3V to +5.5V. Bypass VCC to ground with a 0.1µF capacitor.
3
DXP
Input: Remote-Junction Anode. Place a 2200pF capacitor between DXP and DXN for noise filtering.
4
DXN
Input: Remote-Junction Cathode. DXN is internally biased to a diode voltage above ground.
5
FAN
Open-Drain Output to Fan Low Side. Connect a minimum 1µF capacitor between FAN and VFAN.
6
ADD1
SMBus Address Select Pin. ADD0 and ADD1 are sampled upon power-up.
7 PGND Power Ground
8 AGND Analog Ground
9 OVERT Overtemperature Shutdown Output. Active-low output (programmable for active high if desired). Open drain.
10
ADD0
SMBus Slave Address Select Pin. ADD0 and ADD1 are sampled upon power-up.
11 ALERT SMBus Alert (Interrupt) Output. Open-drain, active-low output.
12 SMBDATA SMBus Serial Data Input/Output. Open drain.
13
GAIN
Gain Control. Connect an external resistor from GAIN to VCC to reduce the gain of the current-sense mode.
14 SMBCLK SMBus Clock Line from Controller. This line tolerates inputs up to VCC even if MAX6660 is not powered.
15
STBY
Hardware Standby Input. Drive STBY low to reduce supply current. Temperature and comparison
data are retained in standby mode.
16 TACH IN Fan Tachometer Input. Tolerates voltages up to VFAN.
Detailed Description
The MAX6660 is a remote temperature sensor and fan
controller with an SMBus interface. The MAX6660 con-
verts the temperature of a remote-junction temperature
sensor to a 10-bit + sign digital word. The remote tem-
perature sensor can be a diode-connected transistor,
such as a 2N3906, or the type normally found on the
substrate of many processors’ ICs. The temperature
information is provided to the fan-speed regulator and
is read over the SMBus interface. The temperature
data, through the SMBus, can be read as a 10-bit +
sign two’s complement word with a 0.125°C resolution
(LSB) and is updated every 0.25s.
The MAX6660 incorporates a closed-loop fan controller
that regulates fan speed with tachometer feedback. The
temperature information is compared to a threshold and
range setting, which enables the MAX6660 to automati-
cally set fan speed proportional to temperature. Full con-
trol of these modes is available, including being able to
open either the thermal control loop or the fan control
loop. Figure 1 shows a simplified block diagram.
ADC
The ADC is an averaging type that integrates over a
60ms period with excellent noise rejection. A bias cur-
rent is steered through the remote diode, where the for-
ward voltage is measured, and the temperature is com-
puted. The DXN pin is the cathode of the remote diode
and is biased at 0.65V above ground by an internal
diode to set up the ADC inputs for a differential mea-
surement. The worst-case DXP-DXN differential input
voltage range is 0.25V to 0.95V. Excess resistance in
series with the remote diode causes about +1/2°C error
per ohm. Likewise, 200mV of offset voltage forced on
DXP-DXN causes approximately 1°C error.
A/D Conversion Sequence
A conversion sequence is initiated every 250ms in the
free-running autoconvert mode (bit 6 = 0 in the
Configuration register) or immediately by writing a One-
Shot command. The result of the new measurement is
available after the end of conversion. The results of the
previous conversion sequence are still available when
the ADC is converting.
Remote-Diode Selection
Temperature accuracy depends on having a good-
quality, diode-connected small-signal transistor.
Accuracy has been experimentally verified for all
devices listed in Table 1. The MAX6660 can also direct-
_______________________________________________________________________________________ 5
5 Page 
Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
Alert Response Address
The SMBus Alert Response interrupt pointer provides
quick fault identification for simple slave devices that
lack the complex, expensive logic needed to be a bus
master. Upon receiving an ALERT interrupt signal, the
host master can broadcast a Receive Byte transmission
to the Alert Response slave address (see Slave
Addresses section). Then, any slave device that gener-
ated an interrupt attempts to identify itself by putting its
own address on the bus (Table 3).
The Alert Response can activate several different slave
devices simultaneously, similar to the I2C™ General
Call. If more than one slave attempts to respond, bus
arbitration rules apply, and the device with the lower
address code wins. The losing device does not gener-
ate an Acknowledge and continues to hold the ALERT
line low until cleared. (The conditions for clearing an
alert vary depending on the type of slave device.)
Successful completion of the Alert Response protocol
clears the interrupt latch, provided the condition that
caused the alert no longer exists. If the condition still
exists, the device reasserts the ALERT interrupt at the
end of the next conversion.
Table 3. Read Format for Alert Response
Address
Command Byte Functions
The 8-bit Command Byte register (Table 4) is the mas-
ter index that points to the other registers within the
MAX6660. The register’s POR is 0000 0000, so that a
receive byte transmission (a protocol that lacks the
BIT
7 (MSB)
6
5
4
3
2
1
0 (LSB)
NAME
ADD7
ADD6
ADD5
ADD4
ADD3
ADD2
ADD1
1
FUNCTION
Provide the current MAX6660
slave address
Logic 1
command byte) that occurs immediately after POR
returns the current remote temperature data.
One-Shot
The one-shot command immediately forces a new conver-
sion cycle to begin. In software standby mode
(RUN/STOP bit = high), a new conversion is begun, after
which the device returns to standby mode. If a conversion
I2C is a trademark of Philips Corp.
is in progress when a one-shot command is received, the
command is ignored. If a one-shot command is between
conversions, in autoconvert mode (RUN/STOP bit = low),
a new conversion begins immediately.
Configuration Byte Functions
The Configuration Byte register (Table 5) is used to
mask (disable) the ALERT signal to place the device in
software standby mode, to change the polarity of
OVERT, to set MAX6660 to thermal open/closed-loop
mode, to inhibit the OVERT signal, to mask OVERT out-
put, and to clear the ALERT signal. The MAX6660 has a
write protection feature (bit 4) that prohibits write com-
mands to bits 6–3 of the Configuration register. It also
prohibits writes to the TMAX, THYST, and Fan
Conversion Rate registers.
Status Byte Functions
The status byte (Table 6) reports several fault condi-
tions. It indicates when the fan driver transistor of the
MAX6660 has overheated and/or is thermal shutdown,
when the temperature thresholds, TLOW and THIGH,
have been exceeded, and whether there is an open cir-
cuit in the DXP-DXN path. The register also reports the
state of the ALERT and OVERT lines and indicates
when the fan driver is fully on. The final bit in the Status
register indicates when a fan failure has occurred.
After POR, the normal state of the flag bits is zero,
assuming no alert or overtemperature conditions are
present. Bits 2 through 6 of the Status register are
cleared by any successful read of the Status register,
unless the fault persists. The ALERT output follows the
status flag bit. Both are cleared when successfully
read, but if the condition still exists, the ALERT is
reasserted at the end of the next conversion.
The MAX6660 incorporates collision avoidance so that
completely asynchronous operation is allowed between
SMBus operations and temperature conversions.
When autoconverting, if the THIGH and TLOW limits are
close together, it is possible for both high-temperature
and low-temperature status bits to be set, depending
on the amount of time between status read operations.
In these circumstances, it is best not to rely on the sta-
tus bits to indicate reversals in long-term temperature
changes. Instead, use a current temperature reading to
establish the trend direction.
Manufacturer and Device ID Codes
Two ROM registers provide manufacturer and device
ID codes. Reading the manufacturer ID returns 4D,
which is the ASCII code M (for Maxim). Reading the
device ID returns 09h, indicating the MAX6660 device.
If READ WORD 16-bit SMBus protocol is employed
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet MAX6660.PDF ] | |
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